Chemicals extracted from corn may one day be used to produce durable, heat-resistant plastic parts, according to Distinguished Professor Kasiviswanathan Muthukumarappan of South Dakota State University’s Department of Agricultural and Biosystems Engineering.
The bioprocessing engineer, who is commonly known as Muthu, formulated star-shaped resins using chemicals from the ethanol fermentation process. These resins, commonly produced from petroleum, are the substances that bond fibers in plastic composite materials.
His resins are unique because they can be used to create composite parts that can withstand harsh conditions and high temperatures. “The resins we developed are belong to the thermoset class,” Muthu said.
Other researchers have developed corn-based resins, which produce thermoplastic materials that can be heated and reformed, he explained. However, these materials can expand and contract, which causes problems for some applications.
Thermoset resin hardens when it cures and cannot then be reheated and reused. That creates composite materials that are more durable and stable in a variety of environments for applications such as equipment panels in automobiles and agricultural machinery components, including gaskets. “When thermosets are required for an application, no thermoplast can do the job,” Muthu pointed out.
The research was funded through a nearly $100,000 grant from the North Central Regional Sun Grant Center. One doctoral student and one master’s student also worked on the project.
“Through advanced processing, we are developing high-value uses for agricultural products that can help producers and boost the agricultural economy in the state and the nation,” said professor Vance Owens, director of the North Central Regional Sun Grant Center.
In 2018, Muthu received $25,000 to support his resin research through the first National Corn Growers Association Consider Corn Challenge. SDSU’s project was one of six finalists among 38 entries in the worldwide competition. “This is an indication of the potential value of this research,” said Muthu, who also sees the potential to produce resins using chemicals from soybean oil.
Utilizing chemicals from ethanol processing
To formulate the corn-based thermoset resins, the SDSU researchers used three chemicals—itaconic acid, ethyl alcohol and lactic acid—produced from what is known as the wet milling process. “Cargill produces these chemicals as part of its ethanol fermentation process,” Muthu said. “The wet milling process can produce a lot of chemicals in addition to the ethanol.”
However, he noted, many ethanol plants now use dry processing, which produces ethanol, dried distillers grain and carbon dioxide.
Approximately 90 bushels of corn produces slightly more than 1.1 tons of corn-based resin. The automotive industry alone uses an estimated 90,000 tons of unsaturated polyester, a specific type of thermoset resin, each year. If corn-based bioresins can capture even 1% of this market, Muthu estimated the revenue share could be about $1.6 million annually.
Based on raw material costs, Muthu anticipates these corn-based resins may be less than half the price of petroleum-based resins.
Further developing corn-based resins
Although the lab testing produced promising results, Muthu said, “there is still a long way to go.”
For the Sun Grant project, the researchers used methacrylic anhydride, which is toxic, to functionalize the chemicals and produce high-viscosity resins. “We want to look for renewable functionalizing agents as well as develop formulations for low-viscosity resins,” he said. The goal is to develop a product that is 100% biobased, nontoxic and biodegradable.
“Resins are a higher value product,” said Muthu, who is applying for further funding to continue the research. “Anything that adds value to agricultural products is beneficial,” Owens concluded.